An Interactive Guide to Mastering Salts
Click to reveal the definition.
A salt is a compound formed when the hydrogen atom in an acid is replaced by a metal. For example, replacing H in HCl with Potassium (K) forms Potassium Chloride (KCl).
Click to see their uses.
Salts have many important uses, including:
Click to learn the rule.
A salt's name has two parts: The first part from the metal/base, the second part from the acid.
1. Which acid produces sulfate salts?
2. What is formed when the hydrogen in an acid is replaced by a metal?
3. Reacting Zinc with Nitric Acid (HNO₃) produces which salt?
4. The salt Copper(II) Chloride is formed from which acid?
5. What is the first part of a salt's name derived from?
6. Which of these is NOT a typical use for salts?
7. What is the chemical formula for the nitrate ion?
8. If you react Magnesium with Sulfuric Acid, what is the name of the salt produced?
9. The chemical formula for sulfuric acid is H₂SO₄. The salt formed contains which ion?
10. A salt is what type of chemical compound?
| Soluble Salts | Exceptions (Insoluble) |
|---|---|
| All Nitrates | None |
| Most Chlorides | Silver & Lead(II) Chloride |
| Most Sulfates | Barium, Calcium & Lead(II) Sulfate |
| Insoluble Salts | Exceptions (Soluble) |
| Most Carbonates | Sodium, Potassium & Ammonium |
| Most Hydroxides | Sodium, Potassium & Ammonium |
1. Is Lead(II) Sulfate soluble or insoluble?
2. Which of the following chlorides is insoluble?
3. According to the rules, which of these salts is always soluble?
4. Is Calcium Carbonate soluble or insoluble?
5. Which of these sulfates is INSOLUBLE?
6. The 'SPA' rule reminds us that salts of Sodium, Potassium and... which other cation... are always soluble?
7. You mix solutions and a precipitate of Barium Sulfate is formed. Is it soluble or insoluble?
8. Which group of salts has no exceptions to its solubility rule?
9. Is Copper(II) Hydroxide soluble or insoluble?
10. Which one of these carbonates is SOLUBLE?
Use for reacting acid with an insoluble metal, metal oxide, metal hydroxide, or metal carbonate.
Acid + Metal → Salt + Hydrogen
Acid + Metal Oxide / Hydroxide → Salt + Water
Acid + Metal Carbonate → Salt + Water + CO₂
Note on Metals: Not all metals are suitable. Some (like Potassium) are too reactive, while others (like Copper) are not reactive enough.
Use for reacting acid with a soluble base (alkali) or soluble carbonate. Needed because you can't see an excess of a soluble substance!
Acid + Alkali → Salt + Water
1. Which technique is used to prepare sodium chloride (a soluble salt) from sodium hydroxide (a soluble base)?
2. In Method A, why is the insoluble reactant added in excess?
3. What is the purpose of the indicator in a titration?
4. To prepare Copper(II) Sulfate from insoluble Copper(II) Oxide, which method is appropriate?
5. What piece of equipment is used to accurately measure a fixed volume of alkali into the flask for titration?
6. After filtering the excess solid in Method A, what is the next step?
7. Why is the titration repeated without the indicator?
8. Which of these reactions using Method A would produce hydrogen gas?
9. The process of forming crystals from a saturated solution is called:
10. Titration is necessary when reacting an acid with a...
This method, called precipitation, involves mixing two soluble salts to form one insoluble salt (the precipitate).
For example, to make insoluble Lead(II) Chloride, you mix soluble Lead(II) Nitrate and soluble Sodium Chloride.
Full Equation:
Pb(NO₃)₂(aq) + 2NaCl(aq) → PbCl₂(s) + 2NaNO₃(aq)
Ionic Equation:
The ionic equation shows only the ions that react. The other ions (Na⁺ and NO₃⁻) are spectator ions and are omitted.
Pb²⁺(aq) + 2Cl⁻(aq) → PbCl₂(s)
1. In the preparation of Barium Sulfate by precipitation, which of these pairs of solutions could be mixed?
2. What is the name given to the solid formed in a precipitation reaction?
3. What is the purpose of washing the precipitate with distilled water?
4. To form insoluble silver chloride, you could mix silver nitrate solution with...
5. In the reaction to form Lead(II) Chloride (PbCl₂), what are the spectator ions?
6. What technique is used to separate the insoluble salt from the solution?
7. Precipitation reactions require the mixing of two...
8. What does an ionic equation show?
9. After washing, how is the precipitate dried?
10. Which state symbol is used for a precipitate in a chemical equation?
This is water that is chemically bonded into the crystal structure of a salt. A salt containing this water is called hydrated.
The formula shows the number of moles of water per mole of salt. E.g., CuSO₄·5H₂O means 5 moles of water are bonded to 1 mole of copper(II) sulfate.
| Feature | Hydrated Salt | Anhydrous Salt |
|---|---|---|
| Contains Water? | Yes | No |
| Example | CuSO₄·5H₂O | CuSO₄ |
Heating a hydrated salt removes the water, which is a reversible reaction:
Hydrated Salt ⇌ Anhydrous Salt + Water
This property is used to test for water:
1. What colour change is observed when water is added to anhydrous cobalt(II) chloride?
2. What is the term for a salt that contains water of crystallisation?
3. What colour is anhydrous copper(II) sulfate?
4. The reaction: Hydrated Salt ⇌ Anhydrous Salt + Water is an example of what?
5. How can you convert hydrated copper(II) sulfate to anhydrous copper(II) sulfate?
6. In the formula CoCl₂·6H₂O, how many moles of water are there for every one mole of cobalt(II) chloride?
7. What is the chemical test for water?
8. What is the name for water that is chemically bonded into a crystal structure?
9. What colour is hydrated copper(II) sulfate?
10. What does the term 'anhydrous' mean?